Memories are a kind of storage for storing digital information, and have memory cells as their basic components, which can store binary information such as “0” and “1”. In the semiconductor industry, the memories play a significant role. In the past decades, semiconductor memories have experienced great developments in both the manufacture technology and the cost control, and are getting more and more market share.
With the popularization of portable digital products such as mobile phones, GPS's, digital cameras, and notebook computers, users are more likely to carry mass data. Other storage mediums such as magnetic disks and optical disks cannot be small-sized and light-weighted while being nonvolatile. In contrast, nonvolatile semiconductor memories can meet both the criteria, and thus are being developed rapidly.
Among the nonvolatile semiconductor memories, nonvolatile resistive switching memories are attracting more attentions due to their features such as high density and low cost. The nonvolatile resistive switching memories store information by the fact that a storage medium thereof has its resistance reversibly switchable between a high-resistance status and a low-resistance status under an electrical signal. There are a variety of such storage mediums, including binary or ternary metal oxides, or even organics. Among those, the binary metal oxides are more attractive because they tend to contain no elements which cause contaminations in the conventional CMOS process and also they result in low power consumption.
Further, the nonvolatile resistive switching memories can be operable only if the resistive memory cells thereof are manufactured together with peripheral circuits thereof. Thus, there is a need for integration of the manufacture of the binary oxide, which constitutes the resistive memory cells of the nonvolatile resistive switching memory, with the conventional CMOS process, to reduce the cost.